Acetylene gas producer



Dec. 14, JONES ACETYLENE GAS PRODUCER Original Filed May 5, 1949INVENTOR.

E. L. JONES A ORNEY United States Patent ACE'FYLENE GAS PRODUCER Edward:L. Jones, Drexel. Hill, Pa., assignor to Phillips Petroleum Companypacorporation of Delaware Originalapplication. May 5, 1949, Serial No.91,540. Digvided and this application July 30, 1951,, Serial No. 23 ,321

1 Claim. (.Cl'. 23-284)- This invention relates to a novel process andapparatus for the partial oxidation of. hydrocarbons. In one of itsmore. specific aspects, it relates toa process for the manufacture ofacetylene and/or mixtures of'carbon monoxide and hydrogen by oxidationof methane.

This application is a division of my copending application Serial No.91,540, filed May 5, 1949, now Patent No. 2,672,488, for PartialOxidation of Hydrocarbons and the claim herein is directed to-theapparatus.

There haslong been a problemof utilizing metal for chambers, tubes,etc'., which must be heated to temperaturesrnuch above 1600 to 1700" F.Many reactions such as the oxidationof methane, or its most readilyavailable form, natural gas, toproduce acetylene, or to produce carbonmonoxide and hydrogen synthesis gas for such processes asFischer-Tropsch synthesis, methanol synthesis, Oxo synthesis (aldehyd'esand alcohols by reacting olefins with synthesis gas), are noteconomically operable at such low temperatures. The. reaction to producecarbon monoxide and hydrogen usually is carried out at temperaturesabove the 2000 F. mark and usually in the range of about 2300 to 2700 F.The reaction to produce acetylene by the partial oxidation of methane isalso preferably carried out at temperatures too high 'tobe withstood bymost metal chambers. An alternative 'method is to utilize a chamber,such as one lined with arefractory material and containing refractorybaffles, blocks, or other arrangements, so. that the outer metal Wall ofthe chamber is protected. In operating such a chamber, a combustiblematerial is usually burned therein to supply heat. The burning is thendiscontinued and the reactants are introduced, utilizing the residentheat for the desired reaction. There are many obvious disadvantages to:such an. arrangement, one specific one being that continuous on-streamreaction may not be maintained due tothe necessary shut downs forreheating.

A still greater disadvantage is that a constant reaction temperaturecannot be maintained thus causing considerable reduction in volume ofproduct.

Anobject of my invention is to provide an improved process: for theoxidation of methane. to produce useful products. Another object of myinvention is to provide a process whereby the oxidation of methane maybe carried out at elevated temperatures usually above 2000 F. Anotherobject is to manufacture acetylene by the partial oxidation of methaneat elevated temperatures. Another object is to make a mixture of carbonmonoxide and hydrogen by the oxidation of methane at elevatedtemperatures. Still another object is to manufacture acetylene and/orsynthesis gas from natural gas. Another object is to provide an.apparatus for the partial oxidation of methane. Another object is toprovide an apparatus for the manufacture of. acetylene and carbonmonoxide and hydrogen. Other objects and advantages of this inventionwill be apparent to one skilled in the art from the. accompanyingdisclosure and discussion.

I have discovered an improved method for oxidizing methane at elevatedtemperatures to. produce acetylene and/or mixtures of carbon monoxideand hydrogen. More specifically, my invention embodies burning methaneor natural gas in a jacketed reaction chamber, the inner wall of whichcontains a large number of small perforations through which water orother coolant and/ or quench is introduced in such a manner that a filmof water or steam is maintained on the. inner surface of manufacturebefore complete oxidation is attained, and in the case of synthesis gasmanufacture at the point where the desired ratio of hydrogen to carbonmonoxide is attained by the water-gas shift reaction. The perforationsin the reaction chamber are necessarily maintained small and preferablyof a relatively uniform size. However, their number and thus their totalcross sectional area should increase in the direction of flow ofreactants through the reaction chamber so that the total flow rate ofmaterial into the chamber per increment of length increases in thedirection of flow' of the reactants.

In one embodiment of my invention, that in which acetylene is theprimary object of manufacture, methane or natural gas and oxygen or airare preheated to a temperature up to about 1000 F., preferablyindividually, and then admixed and introduced to a reaction chamber ofthe type hereinafter described. The pressure maintained within thechamber is not too critical, however, in a preferred embodiment it isdesirable to maintain a pressure of from atmospheric to say 1500 p. s.i., and preferably in the range of atmospheric to 1000 p. s. i. Thereactants are introduced to the chamber in such proportions and burnedtherein in such a manner that the methane is partially oxidized at atemperature in the broad range of 1300 to 5000 F., but preferably inthe. range of 3000 to 5000 F. It is always necessary to use a quantityof oxygen less than the theoretical. amount required for completecombustion of the hydrocarbon in the feed, however, there must be enoughpresent to provide sufiicient heat to maintain the desired reaction. Asuitable contact time for the reactants is 0.10 to 0.005 second andspecifically about 0.04 second. Following the brief cont-acting, thematerials are rapidly quenched to a temperature at least as low as 1000F. by suitable means such as steam or other gas such as nitrogen orcarbon dioxide. For the production of maximum yields of acetylene, thehighest possible temperature and shortest contact time should be used.

The reaction chamber utilized for the above described reaction may beconstructed of any metal which will withstand the high temperaturesgenerated by the reaction. For example, high carbon steel or steelcontaining small amounts of tungsten or molybdenum is very satisfactory.It is well known that at present no available metal will withstandtemperatures in the neighborhood of 5000 F. and for this reason, I haveprovided numerous perforations in the reaction chamber to allow thepassage of water or other cooling and/ or quench materials previouslynamed. When operating in this manner, the inner perforate reactionchamber is jacketed to provide a space for containing the coolant. Theinner chamber is so constructed that the coolant for the metal reactionchamber is also the quench material for the reaction products.

As the coolant and quench material are continuously introduced throughthe small perforations of the chamber, it forms a protective layer alongthe inner wall. When the temperatures are relatively low, this layer orfilm may be water when water is used, but at the higher temperatures, itwill be steam or other gas. The charge stocks to the reaction may bepreheated by means of heat exchange with the effluent products. Theadvantage of using steam as a quench for the acetylene is that the twomay be separated by condensing the steam. The attached drawings and thediscussion thereof will show further how the cooling and quench materialmay be passed through the inner shell of the reaction chamber.

In the practice of my process for the production or acetylene, yields inthe range of 6 to 10 per cent may be obtained when using oxygen ratherthan air. The yield may even range upward to 20 per cent whensufficiently high temperatures are used.

In the second embodiment of my invention wherein the major purpose is toproduce hydrogen and carbon monoxide such as for use in synthesis gas,the following general procedure'is carried out. In this embodiment as inthe one wherein the major object is to produce acetylene, the reactionapparatus is the same, however, the conditions are altered somewhat. Inthis embodiment, natural gas or methane and oxygen or air are preheatedto about 1000 F. and admixed with one another prior to introduction tothe reaction chamber. The admixture is then introduced to the reactionzone where the hydrocarbon is partially oxidized at a temperature in therange of 2000 to 2700 F. and a pressure in the range of atmospheric tosay 800 p. s. i. Preferred ranges of temperature and pressure are 2300to 2500 F. and 50 to 400 p. s. i. Suitable contact times areconsiderably longer than those applicable in the production of acetyleneand fall within the range of, say, 0.02 to 2 sec onds and preferably 0.1to 1.5 seconds. When synthesis gas is the major product, it is desirableto produce it at pressures similar to those at which it is to used.However, this may not be feasible in all cases since some processesusing hydrogen and carbon monoxide as a charge stock, such as the x0process, are operated at quite high pressures. When the synthesis gas isused for such processes, it is preferable to make it at as highpressures as possible and then to compress it to the pressures required.By so operating, a minimum of compression of the synthesis gas isrequired.

When making synthesis gas several different coolants may be used toprotect the walls of the reaction chamber and to quench the products.For example, liquid oxygen, liquid carbon dioxide, water, liquidnitrogen, etc., may be used depending somewhat on the ratio of hydrogento carbon monoxide desired. It is known that the use of steam in themanufacture of synthesis gas will increase the Hz/CO ratio while the useof carbon dioxide will decrease same. Oxygen will not change the ratioand neither will nitrogen or other inert materials. Although the abovematerials have been mentioned as cooling and quenching agents, it isapparent that while quenching the synthesis gas some of them will reactwith it and will exert a considerable eifect on the ratio of Hz/CO bymeans of the water gas shift reaction which is represented by thefollowing Equation 1:

As discussed above, steam will make the reaction go to the left thusincreasing the proportion of hydrogen, and carbon dioxide will make itgo to the right, producing the opposite effect.

A more clear understanding of some of the many aspects of my inventionmay be had by referring to the attached drawings. Figure l is alongitudinal cross-sectional view of myapparatus in conjunction with afiow diagram. Figures 2 and 3 are cross sections through the reactionchamber of Figure 1 taken along lines 2-2 showing three differentarrangements of inlets for the cooling and quench material. Figure 4 issimilar to Figures 2 and 3 with a different positioning of the inlets tothe reaction chamber. Similar portions of the apparatus in the severaldrawings are similarly numbered.

Refer now to Figure 1. Natural gas and air which supply the methane andoxygen for either the production of acetylene or hydrogen and carbonconoxide synthesis gas are passed via lines and 11 to heat exchangers 12where they are preheated to a temperature up to about 1000" F. byindirect heat exchange with the quenched reaction products. From theheat exchangers, the preheated natural gas and oxygen are passed vialines 13 and 14 to line 15 in which they are admixed and through whichthey are passed to concave burner 21 inside the reaction chamber.

Number 16 indicates the elongated cylindrical perforate steel reactionchamber within which the partial oxidation and dehydrogenation reactionstake place to produce synthesis gas and acetylene. The inlet end of saidchamber is preferably in a dome shape, while the opposite end ispreferably of ever decreasing radius and in somewhat of a cone shape.Number 17 indicates the outer steel shell which forms the jacket aroundchamber 16 providing space 28 therebetween. Numbers 29 indicate theuniformly spaced circumferentially positioned inlets for the coolantlying in planes passing at right angles through the axis of the reactionchamber. These inlets may be either at right angles to the surface ofthe chamber or may be positioned along the plane passing therethroughwhich is at a right angle with the axis of the chamber. The total crosssectional area of these inlets increases in the direction of flow ofmaterials through said chamber. In this way, more coolant and quenchmaterial is introduced progressively in the downstream direction. Wateror other cooling and quenching material is passed via line 18 to lines19 and 20 through which it is introduced to space 28 between chamber 16and jacket 17. A final quench inlet, number 22, is provided for thereaction products in the outlet from the reaction chamber between theends of the reaction chamber and jacket. This is utilized to insurecooling of the products to 1000 F. or below. The product materials arepassed via line 23 to turbine 24 where the pressure is utilized for thegeneration of power. After passing through turbine 24, the productmaterials are passed through line 25 to a storage unit or to aseparation and recovery unit. A portion of the product is passed fromline 25 via line 26 to heat exchanger 12 by means of blower 30. Afterheating the natural gas and air, the cooled product gases are passed vialine 27 back to line 25 at a point downstream from the point at whichthe gas was removed.

It is within the scope of my invention that the reaction chamber may beof a design other than cylindrical and that the ends may also be ofshapes other than those specifically described. However, for bestoperation and pressure resistance, the design as disclosed is preferred.Also the position of the perforations may be other than radial such astangential, see Figure 4, all pointing in the same direction, ortangential with each perforation pointing in the opposite direction tothe one next to it as shown in Figure 3.

Refer now to Figure 2 which illustrates one embodiment of the coolantand quench material inlets 29. Number 17 is the outer jacket axiallypositioned with respect to reaction chamber 16. Space between these twointo which the coolant and quench material is introduced is numbered 28.Number 29 indicates radially positioned perforations in the wall ofchamber 16 through which the coolant and quench material are passed fromspace 28. This positioning of the perforations enables the coolant tonot only protect the reaction chamber walls, but to also diffuse intothe reaction zone and react with the other materials present.

Figure 4 is similar to Figure 2 except for the position of the coolantand quench inlets. These inlets 29 have been placed in a substantiallytangential position with respect to reaction chamber 16 so that a betterblanket of coolant may be maintained along the inner walls of thereaction chamber. The coolant travels around the walls of the chamberwhen introduced in this manner and does not admix with the othermaterials as rapidly. It may be desirable in certain instances toconstruct the reaction chamber so that the coolant and quenchinletsclosest to the burner are positioned as shown in Figure 3 andthose downstream from the burner positioned as shown in Figure 2. Inthis manner more complete protection of the reaction chamber is had.

Figure 3 is also similar to Figure 2 except for the position of theinlets. In this embodiment, the inlets 29 are placed in an angularposition, every other inlet pointing in the opposite direction from theadjoining inlet. In this manner a thicker turbulent layer of protectivecoolant is provided. It is also within the scope of my invention to usecombinations of inlets shown in Figures 2-4 to provide adequate coolingand quenching at all parts of the reaction chamber.

Advantages of this invention are illustrated by the following example.The reactants and their proportions are presented as being typical andshould not be construed to limit the invention unduly.

Example Natural gas, containing volume per cent methane, and oxygen, ina volume ratio of 3 to 1, are preheated separately to 700 F. The twopreheated materials are then admixed and introduced to a reactor as Ihave previously described wherein the methane is partially oxidized at atemperature of 3800 F. and under a pressure of 500 p. s. i. The contacttime used is 0.01 second. The reaction products are quenched with steamintroduced through the perforations of the reaction chamber walls to 950F. The quenched products are then passed to a recovery process whereinthe acetylene, synthesis gas, and steam are separated. By operating inthis manner, a product comprising about 8 volume per cent acetylene isobtained.

An additional advantage of using this process and apparatus is that aninert diluent such as nitrogen usually required for the manufacture ofacetylene from natural gas is done away with by the use of oxygen toburn with the natural gas and the use of a quench material such as waterwhich acts as a diluent and which may be condensed, and easilyseparated. By proceeding in the above described manner, separation ofthe reaction products is much more easily accomplished.

Although this invention has been described and exemplified in terms ofits preferred modifications, it is understood that various changes maybe made without departing from the spirit and scope of the disclosureand of the claim.

I claim:

An apparatus wherein the partial oxidation of methane may be carried outwhich comprises an elongated cylindrical chamber, formed from a metalwhich will withstand the temperature of the partial oxidation reaction,one end being of a substantially dome shape and the second end having anever-decreasing diameter, an axially positioned outer jacket for saidchamber forming a space therebetween, an axially positioned inlet meansto said chamber extending through said jacket, an axially positionedconcave burner within said chamber attached to said inlet, a pluralityof circumferentially positioned perforations in the walls of saidchamber the number and total cross sectional area of which increases perunit length in the direction of flow of materials through said chamber,means for introducing a cooling and quenching material to said space andfor passing same through said perforations and into said chamber, anoutlet from said chamber for materials introduced thereto through saidinlet and through said perforations, and radially positioned inlet meansin said outlet positioned between the end of said chamber and saidjacket for introducing additional material from said space.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,417,835 Moore Mar. 25, 1947 2,552,492 Nathan May 8, 19512,575,264 Feilden Nov. 13, 1951 2,621,117 Garrison Dec. 9, 1952

